CVE-2023-53089

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ext4: fix task hung in ext4_xattr_delete_inode<br /> <br /> Syzbot reported a hung task problem:<br /> ==================================================================<br /> INFO: task syz-executor232:5073 blocked for more than 143 seconds.<br /> Not tainted 6.2.0-rc2-syzkaller-00024-g512dee0c00ad #0<br /> "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.<br /> task:syz-exec232 state:D stack:21024 pid:5073 ppid:5072 flags:0x00004004<br /> Call Trace:<br /> <br /> context_switch kernel/sched/core.c:5244 [inline]<br /> __schedule+0x995/0xe20 kernel/sched/core.c:6555<br /> schedule+0xcb/0x190 kernel/sched/core.c:6631<br /> __wait_on_freeing_inode fs/inode.c:2196 [inline]<br /> find_inode_fast+0x35a/0x4c0 fs/inode.c:950<br /> iget_locked+0xb1/0x830 fs/inode.c:1273<br /> __ext4_iget+0x22e/0x3ed0 fs/ext4/inode.c:4861<br /> ext4_xattr_inode_iget+0x68/0x4e0 fs/ext4/xattr.c:389<br /> ext4_xattr_inode_dec_ref_all+0x1a7/0xe50 fs/ext4/xattr.c:1148<br /> ext4_xattr_delete_inode+0xb04/0xcd0 fs/ext4/xattr.c:2880<br /> ext4_evict_inode+0xd7c/0x10b0 fs/ext4/inode.c:296<br /> evict+0x2a4/0x620 fs/inode.c:664<br /> ext4_orphan_cleanup+0xb60/0x1340 fs/ext4/orphan.c:474<br /> __ext4_fill_super fs/ext4/super.c:5516 [inline]<br /> ext4_fill_super+0x81cd/0x8700 fs/ext4/super.c:5644<br /> get_tree_bdev+0x400/0x620 fs/super.c:1282<br /> vfs_get_tree+0x88/0x270 fs/super.c:1489<br /> do_new_mount+0x289/0xad0 fs/namespace.c:3145<br /> do_mount fs/namespace.c:3488 [inline]<br /> __do_sys_mount fs/namespace.c:3697 [inline]<br /> __se_sys_mount+0x2d3/0x3c0 fs/namespace.c:3674<br /> do_syscall_x64 arch/x86/entry/common.c:50 [inline]<br /> do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80<br /> entry_SYSCALL_64_after_hwframe+0x63/0xcd<br /> RIP: 0033:0x7fa5406fd5ea<br /> RSP: 002b:00007ffc7232f968 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5<br /> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fa5406fd5ea<br /> RDX: 0000000020000440 RSI: 0000000020000000 RDI: 00007ffc7232f970<br /> RBP: 00007ffc7232f970 R08: 00007ffc7232f9b0 R09: 0000000000000432<br /> R10: 0000000000804a03 R11: 0000000000000202 R12: 0000000000000004<br /> R13: 0000555556a7a2c0 R14: 00007ffc7232f9b0 R15: 0000000000000000<br /> <br /> ==================================================================<br /> <br /> The problem is that the inode contains an xattr entry with ea_inum of 15<br /> when cleaning up an orphan inode . When evict inode , the reference<br /> counting of the corresponding EA inode is decreased. When EA inode is<br /> found by find_inode_fast() in __ext4_iget(), it is found that the EA inode<br /> holds the I_FREEING flag and waits for the EA inode to complete deletion.<br /> As a result, when inode is being deleted, we wait for inode to<br /> complete the deletion, resulting in an infinite loop and triggering Hung<br /> Task. To solve this problem, we only need to check whether the ino of EA<br /> inode and parent is the same before getting EA inode.